Chiral azetidinone derivatives, and their use as dopes in liquid-crystal mixtures
AssigneeHoechst Aktiengesellschaft
InventorsGunter Scherowsky, Claas Junghans, Anke Kaltbeitzel, Rainer Wingen, Britta Michalski
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Abstract
Azetidinones of the formula I ##STR1## in which, for example, R.sup.1 is an alkyl or alkenyl radical, R.sup.2 and R.sup.3 are hydrogen or an alkyl or alkenyl radical, Z is hydrogen or (pseudo)halogen, A.sup.1, A.sup.2 and A.sup.3 are a ring system, and M is a spacer group, can be added to liquid-crystal mixtures. Even when admixed in small amounts, they cause considerable twist in the cholesteric and smectic C* phase, which can compensate the pitch of another dope or produce a short S.sub.C * pitch.
Claims5
An azetidinone of the formula I ##STR21## in which the symbols and indices have the following meanings:
- (*) indicates a possible chiral center,
- R.sup.1 is a straight-chain or branched alkyl radical having 1 to 16 carbon atoms, in which one or more non-adjacent --CH.sub.2 -- groups may be replaced by --O--, --O--CO-- or --CO--O--, which correspondingly reduces the number of carbon atoms in the radical,
- R.sup.2 is a hydrogen atom or an alkyl radical having 1 to 10 carbon atoms,
- R.sup.3 is a hydrogen atom or an alkyl radical having 1 to 10 carbon atoms,
- Z is H,
- j and l are 0, 1 or 2,
- k and m are 0 or 1, and
- n is 0, 1 or 2,
- with the following proviso:
- if j and/or l are zero, k is zero;
- if n is zero, m is zero;
- the sum of j+l+n is at least 1 and at most 3,
- --A.sup.1 and --A.sup.2 are selected from the group consisting of ##STR22## --A.sup.3 is selected from the group consisting of ##STR23## and --M.sup.1 and --M.sup.2 are --O--CO-- or --CO--O--.
Dependencies are inferred from the claim text.